DIAGNOSIS Excessive strain on the belt. Primary cause is not clearing hair from the brush roll ends and bearings.
FIX Every time you replace belt, also remove the brush roll. Use scissors to cut away all hair and thread wrapped around the metal shaft ends and the plastic bearings. Reinstall. Use only Genuine Bissell Belt 1610693.
IF THAT DIDN'T WORK The brush roll itself may be bent or the bearings seized, creating massive drag. Spin roll by hand. It must spin freely.
HEADS UP Never run vacuum with a stuck brush roll. That snaps a belt instantly and can overheat motor.